Numerical analysis of thermal-hydraulic influence of geometric flow baffles on multistage Tesla valves in printed circuit heat exchangers

Abstract

The innovative structure and flexible functionality of Tesla valves have attracted significant attention across various industries. Unlike conventional check valves, which open in response to fluid movement and pressure and close to prevent backflow, Tesla valves utilize interconnected pathways to create a highly efficient and reliable method for regulating fluid flow. However, the thermal–hydraulic influence associated with the utilization of different geometric configurations of flow baffles in Tesla valves remain incompletely understood. This study employs numerical simulations to assess the effectiveness of a printed circuit heat exchanger (PCHE) incorporating three layers of multistage Tesla valves with geometric flow baffles. The simulations, based on solving the Navier-Stokes and energy equations, focus on analyzing the behavior of liquid water within a temperature range of 30 to 90 °C, pertinent to applications such as geothermal heating systems. The employed Tesla valve configuration demonstrates superior performance, exhibiting a notable enhancement in thermal effectiveness ranging from 13 % to 55 % compared to configurations utilizing zigzag, separate, and overlapping NACA 0020 airfoils under otherwise identical conditions. Three crucial geometric parameters are introduced to characterize the shape of flow baffles in multistage Tesla valves: the length from the baffle apex to the baffle half-front sphere, the radius of the baffle half-front sphere, and the distance from the baffle apex to the centerline of the entrance flow channel. Performance evaluation criteria (PEC) indicate that while the overlapping airfoil configuration performs better than both zigzag and separate configurations, the current Tesla valve design achieves approximately a 10–14 % higher PEC value than the overlapping airfoil configuration. The manipulation of geometric parameters for flow baffles is generally believed to be a critical step in the advancement of multistage Tesla valves, contributing to the enhancement of heat transfer and potentially broadening the applicability of these valves to various practical heat transfer systems.